Unlike humans, salamanders can re-grow lost limbs. Essentially, all their cells are stem cells, blank slates capable of becoming any type of tissue. Now, scientists are tapping the same possibilities in human adult stem cells in order to repair tendons, ligaments and cartilage. It sounds like something straight out of science fiction, but this promising new field—called regenerative medicine—is poised to revolutionize the world of medicine.

“Adult stem cells are those that have not yet differentiated into a kind of tissue,” says physiatrist Marc Darrow, MD, Associate Clinical Professor of Medicine at UCLA School of Medicine, who specializes in physical medicine and rehabilitation.

“Theoretically, stems cells can become any tissue type. They work well in healing tears in tissue or worn-down cartilage primarily because the human body is made of collagen, and stem cells repair collagen.” Collagen is a protein component of cartilage.

Harvesting adult stem cells

Adult stem cells—most plentiful in bone marrow and body fat—are taken from a patient’s body. Healing is easiest when the cells are taken from marrow, says Darrow: “The fat extraction process is laborious, involving lipoaspiration”—the removal of fat by suction—“and that can lead to bruising.” Injecting stem cells taken from fat into a patient also requires a larger needle than marrow stem cells do because fat is thick.

“The extraction of adult stem cells from a patient often takes less than five minutes once the area is numbed with a local anesthesia,” says Darrow. A needle is injected into the back of the pelvis, and the marrow is withdrawn into syringes. The cells are then centrifuged, or spun, for 15 minutes to separate the stem cells from the blood.

Reinserting adult stem cells

Once the adult stem cells have been harvested, they are injected into the same patient they were taken from. “I make several injections implanting a small amount of stem cells into an affected joint or other affected area to spread the solution evenly,” says Darrow. Injecting a large amount in one area can cause hematomas, or a swelling of clotted blood. No anesthesia is needed.

Because the stem cells are simply harvested and then re-implanted, the procedures align with FDA guidelines that prohibit the manipulation of stem cells.

Regrowth begins

Cells where the stem cells are inserted send signals, or biochemical compounds called growth factors, to the adult stem cells. In turn, the adult stem cells respond with their own signals sent to their nuclei where the DNA of the differentiated cells, say, in the joint cartilage, is transcribed.

“New tissue growth continues for months after an injection,” says Darrow. “Although some patients feel better soon, others require a few treatments for the pain to resolve.”

Although adult stem cell therapy, or regenerative therapy, is now used all over the world, says Darrow, it is not yet covered by health insurance.“My [fee] for stem cell therapy is $1800,” says Darrow. Costs vary depending on the practitioner and on what area of the body is treated.

Risks are minimal, says Darrow: “When adult stem cells are injected into their donor, there is not DNA rejection, infection, or disease transfer as long as the patient is healthy.” The risks are the same as those of any injection, says Darrow: infections or misguided needle insertions.

Says Darrow, “Anyone with musculoskeletal pain is a candidate for the procedure.”